On the Superior Activity of In(I) versus In(III) Cations Toward <i>ortho-C-</i>Alkylation of Anilines and Intramolecular Hydroamination of Alkenes

Abstract

An efficient <i>ortho</i>-<i>C</i>-alkylation of unprotected anilines with a variety of styrenes and alkenes using a univalent cationic indium(I) catalyst is reported. Mechanistic studies revealed that the reaction likely proceeds via a tandem hydroamination/Hofmann-Martius rearrangement. The high compatibility between the cationic indium(I) complex and primary anilines led us to develop an In(I)⁺-catalyzed hydroamination of alkenes using unprotected primary and secondary alkenylamines. Computations support the catalytic activity of naked In(I)⁺ ions, with an outer sphere mechanism for the C-N bond formation and a potentially inner sphere protodemetallation.